Enhances GitHub Actions workflows by adding a benchmarking workflow for .NET 8 and 9, updating existing workflows, and including a new benchmark project.

[shinji-san]

This pull request includes several changes to the GitHub Actions workflows, the solution file, and the addition of benchmarking for the LuhnDotNet project. The most important changes include the addition of a new benchmarking workflow, updates to existing workflows, and the inclusion of a new benchmark project in the solution.

GitHub Actions Workflows:

• Added a new workflow to run Benchmark.Net for LuhnDotNet, which includes setting up .NET 8 and .NET 9, running the benchmark project, and storing the benchmark results. This workflow is named LuhnDotNet - Benchmark.Net (.github/workflows/benchmarkdotnet.yml).
• Updated the docfx-build-and-publish.yml workflow to trigger on the completion of the LuhnDotNet - Benchmark.Net workflow, set up .NET 9, update and run docfx, and copy benchmark results to the _site directory for publishing (.github/workflows/docfx-build-and-publish.yml). [1] [2] [3]
• Renamed existing workflows for better clarity:
  • LuhnDotNet (All supported TFM) to LuhnDotNet - Build and Test All .NET Versions (.github/workflows/dotnetall.yml).
  • LuhnDotNet NuGet to LuhnDotNet - NuGet Publishing (.github/workflows/publishing.yml).
  • CodeQL to LuhnDotNet - CodeQL (.github/workflows/codeql-analysis.yml).

Solution File:

• Added the LuhnDotNetBenchmark project to the solution file LuhnDotNet.sln to include the new benchmark project (LuhnDotNet.sln). [1] [2]

Benchmark Project:

• Added a new benchmark project LuhnDotNetBenchmark with benchmarks for computing and validating Luhn numbers using both string and span inputs (benchmark/LuhnDotNetBenchmark.cs, benchmark/LuhnDotNetBenchmark.csproj, benchmark/Program.cs). [1] [2] [3]

Documentation:

• Updated the table of contents to include a link to the benchmark results (toc.yml).